A display device for the passengers in the rear seats of an automobile has, for example, a base member provided on the ceiling of the vehicle and a display device provided on a cover member, and the cover member, on which the display member is provided, is connected by a hinge device so that the cover member can be opened, closed, stopped, and retained at an angle making the display easy to be watched. It is desirable for the hinge device to be constructed, for example, such that a relatively low rotational torque (resistance torque) is applied at a start position, that a relatively high rotational toque is applied at an intermediate position, and that a maximum torque capable of maintaining a stopped state is applied at a normal use position. A known conventional hinge device of this type is equipped with: a fixing member provided with a recess and a hole in the rotating direction; a braking member formed of an elastic material and provided with an arm portion extending toward the outer periphery from the rotation center portion, with a protrusion being provided at a free end of the arm portion; and an elastic member for holding the braking member in press contact with the fixing member. High torque is applied to the region where the protrusion of the braking member is held in sliding contact with the fixing member. Low torque is applied to the region where sliding contact of the protrusion is avoided by virtue of the peripheral recess. Maximum torque is applied when the protrusion having dropped into the hole climbs up (see, for example, Patent Document 1).
The operation of this conventional hinge device will be described with reference to FIG. 14.
A range from an angle of 0°, at which a display device 11 is accommodated in a ceiling 12, to an angle of 30° (range T1), is a low-torque range where sliding contact of the protrusion of the braking member is avoided due to the peripheral recess. When the lock is canceled, the display device 11 drops (opens) by substantially 30° due to its own weight. The next range from approximately 30° to 105° (range T2) is a high-torque range where the protrusion of the braking member is held in sliding contact with the fixing member and where manual operation is performed to allow free stop. A normal use position (position T3), where the display device 11 is watched, is a region where maximum torque is generated through transition from fit-engagement to non-fit-engagement (i.e., the protrusion climbs up from the fit-engagement state) of the protrusion of the braking member with the hole of the fixing member and where no positional deviation is caused by vibration, etc. of the vehicle.
Patent Document 1: JP 2003-56547 A